Question

Is it possible to make a function that unsets a variable when it is used X time(s)?

I’m aware of unset() and how it works.
This would be handy for the security sake.

For example to automaticlly unset personal information that I obtained from a MySQL database, having 1000-2000 unset() in the code just looks so messy!

Answer 1

Although your question doesn’t make perfectly sense here’s a possibility to do it:

class ExpiredValue {
    private $data;
    private $access_counter;
    private $max_access;

    public function __construct($data, $max_access) {
        $this->max_access = $max_access;
        $this->__invoke($data);
    }

    public function __invoke($data = null) {
        if(func_num_args() == 0) {
            $this->access_counter++;
            if($this->access_counter > $this->max_access) {
                $this->data = null; // remove data from memory
            }
            return $this->data;
        } else if(func_num_args() == 1) {
            $this->access_counter = 0;
            $this->data = $data;
        }
    }
}

How to use:

$value = new ExpiredValue("<data>", 3);
echo $value(); // "<data>"
$value("<other data>");
echo $value(); // "<other data>"
echo $value(); // "<other data>"
echo $value(); // "<other data>"
echo $value(); // null

Mostly if you begin to think about stuff like this you’re on the wrong way. It sometimes helps to take a step back and figure out what the real problem is. Your problem is not really that there is not a good possibility to expire your variables.